Surveying system, scanner device, target unit, and surveying method

ABSTRACT

A surveying system includes a target unit having a reflection target and an encoder pattern showing an angle of the target unit; a scanner configured to acquire three-dimensional point cloud data, measured coordinates of the target, and optically read the encoder pattern to acquire an encoder pattern read angle; and a leveling base configured to selectively allow either of the target unit and the scanner to be removably mounted. The scanner calculates a direction angle of the leveling base based on the encoder pattern read angle and the offset angle of the target unit, calculates coordinates of an installation point of the target unit based on the measured coordinates of the target and the direction angle of the target, and calculates a direction angle of the scanner based on the offset angle of the scanner and the direction angle of the leveling base on which the scanner is mounted.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2018-185898 filed Sep. 28, 2018. Thecontents of this application are incorporated herein by reference intheir entirely.

TECHNICAL FIELD

The present invention relates to a surveying method, more specifically,to a surveying system using a ground-installed laser scanner, a scannerdevice, a target unit, and a surveying method.

BACKGROUND ART

A ground-installed scanner device is mounted on a tripod, and used tograsp three-dimensional shapes of terrain and features by acquiringthree-dimensional observation data including three-dimensional pointcloud data of a measuring object by rotationally irradiating laserpulsed light via a scanning unit, scanning the measuring object, andperforming a distance measurement and an angle measurement by eachpulsed light.

Point cloud data obtained with the ground-installed scanner device is ina coordinate system centered at the scanner. Therefore, to integratepoint cloud data obtained at a plurality of observation points, theacquired point cloud data need to be converted into a common absolutecoordinate system. Therefore, it is necessary to measure absolutecoordinates and direction angles of the scanner device at theobservation points (for example, Paragraph 0008, etc., in PatentLiterature 1).

For this, a backward intersection method and a method using a backsightpoint and an instrument point are available, and general procedures ofthese methods are as follows.

When using a backward intersection method:

1. Install reflection targets at two or more known points.2. Install a ground-installed scanner at a location where point clouddata are observed.3. Target-scan each reflection target, and measure a distance and adirection angle to each target.4. Observe (full-dome scan) point cloud data.5. Install the ground-installed scanner at a location (new point) wherepoint cloud data are newly observed.6. Install the reflection targets at new known points as necessary.7. Repeat steps 3. to 6. described above.8. Obtain respective instrument point coordinates and instrumentdirection angles by the backward intersection method, and convertrespective point cloud observation data into coordinate values in acoordinate system used for the known points.

When using a backsight-point-and-instrument-point method:

1. Install a reflection target at a backsight point (known point), andinstall a ground-installed scanner at an instrument point (being a knownpoint and a location where point cloud data are observed).2. Install a reflection target at a location (new point) where pointcloud data are observed next.3. Respectively target-scan the reflection target at the backsight pointand the reflection target at the new point, and measure distances anddirection angles to the targets.4. Observe (full-dome scan) point cloud data.5. Install the ground-installed scanner at the new point described instep 2.6. Install a reflection target at the last instrument point as abacksight point.7. Repeat steps 2. to 6. described above.8. Obtain instrument point coordinates (known) and a direction angle atthe first backsight point, and successively obtain instrument pointcoordinates and instrument direction angles, and convert point cloudobservation data at each instrument point into coordinate values in acoordinate system used for the known points.

CITATION LIST Patent Literature [Patent Literature 1] Japanese PublishedUnexamined Patent Application No. 2018-004401 SUMMARY OF INVENTIONTechnical Problem

However, in these methods, when a next observation point (new point) isset, it is necessary to install reflection targets at two or more knownpoints in the backward intersection method and a reflection target at aknown point being a backsight point abacksight-point-and-instrument-point method, in addition to install areflection target at the new point, and then perform target scanning.

A time necessary for target scanning is approximately 2 minutes for onereflection target, and this becomes a factor of an increase in timenecessary for the overall observation operation.

Further, with the conventional methods, particularly in an environmentsuch as an indoor environment having a large number of walls, etc.,obstructing the vision, the following problems occur. In the backwardintersection method, when preparing two or more known points in a rangeviewable from a new instrument point in advance, fewer known points canbe shared, the known point setting operation increases, and theoperation becomes troublesome.

In the backsight-point-and-instrument-point method, a next instrumentpoint (new point) must always be set in a range from which a backsightpoint is viewable, so that a ground-installed scanner cannot beinstalled at a location optimum for observation in some cases, so thatthe number of observations needs to be increased to acquire necessarydata, and the operation becomes troublesome.

The present invention was made in view of the above-describedcircumstances, and an object thereof is to provide a surveying systemcapable of determining a new point, less or without performingmeasurement of a known point or a backsight point in a survey using aground-installed scanner.

Solution to Problem

In order to solve the above-described problems, a surveying systemaccording to an aspect of the present invention includes: a target unitincluding a reflection target and an encoder pattern showing an angle ina circumferential direction around a central axis of the target unit; ascanner device including a distance measuring unit configured to performa distance measurement by transmitting distance measuring light andreceiving reflected light, a scanning unit configured to rotationallyirradiate the distance measuring light onto a measurement range, and anangle detector configured to detect an irradiation direction of thedistance measuring light, so as to acquire point cloud data and acquiremeasured coordinates of the reflection target by performing targetscanning, the scanner device including an encoder pattern reading unitconfigured to optically read the encoder pattern, and an arithmeticcontrol unit configured to operate an encoder pattern read angle basedon a result of encoder pattern reading; and a leveling base configuredto selectively allow either of the target unit and the scanner device tobe removably mounted so as to share a central axis in the verticaldirection, and having offset angles, being known, around the centralaxis with respect to each of the target unit and the scanner device whenthe target unit or the scanner device is mounted, wherein the arithmeticcontrol unit calculates a direction angle of the leveling base based onthe encoder pattern read angle of the target unit installed by mountingon the leveling base and the offset angle of the target unit, andcalculates coordinates of an installation point of the target unit basedon the measured coordinates of the reflection target of the target unitinstalled by mounting on the leveling base and the direction angle, andthe arithmetic control unit calculates a direction angle of the scannerdevice based on the offset angle of the scanner device and the directionangle of the leveling base on which the scanner device is mounted.

A scanner device according to another aspect of the present inventionincludes: a distance measuring unit configured to perform a distancemeasurement by transmitting distance measuring light and receivingreflected light; a scanning unit configured to rotationally irradiatethe distance measuring light onto a measurement range; an angle detectorconfigured to detect an irradiation direction of the distance measuringlight; and an encoder pattern reading unit configured to optically readan encoder pattern provided in a target unit, the target unit includinga reflection target and removably mounted on a leveling base so as toshare a central axis in the vertical direction, and the encoder patternshowing an angle in a circumferential direction around the central axisof the target unit; and an arithmetic control unit, and the scannerdevice removably mounted on the leveling base so as to share the centralaxis in the vertical direction, wherein the leveling base has offsetangles, around the central axis when the scanner device or the targetunit is mounted, and the offset angles being known, the arithmeticcontrol unit acquires point cloud data and operates measured coordinatesof the reflection target by target-scanning the reflection target,operates the encoder pattern read angle from a result of reading of theencoder pattern of the target unit mounted on the leveling base, andbased on the encoder pattern read angle and the offset angle of thetarget unit, operates a direction angle of the leveling base, calculatescoordinates of an installation point of the target unit based onmeasured coordinates of the target unit installed by mounting on theleveling base and the direction angle, and calculates a direction angleof the scanner device based on the offset angle of the scanner deviceand the direction angle of the leveling base on which the scanner deviceis mounted.

A target unit according to another aspect of the present inventionincludes a reflection target and an encoder pattern showing an angle ina circumferential direction around a central axis of the target unit,and is configured to be removably mounted on a leveling base so as toshare a central axis in the vertical direction, and configured to be, ina mounted state on the leveling base, positioned in a circumferentialdirection around the central axis and have an offset angle, being known,around the central axis.

A surveying method according to another aspect of the present inventionincludes the steps of:(a) a scanner device calculating a direction angleof the scanner device based on an offset angle θ_(S) of the scannerdevice around a vertical central axis with respect to a leveling base,the scanner device mounted on the leveling base installed at a positionP_(i) whose coordinates and direction angle are known; (b) the scannerdevice scanning, at the point P_(i), a reflection target of a targetunit mounted on the leveling base installed at a point P_(i+1) to beobserved next, and operating measured coordinates of the reflectiontarget; (c) the scanner device reading an encoder pattern of the targetunit installed at the point P_(i+1), and operating an encoder patternread angle θ_(E) based on a result of reading; (d) the scanner deviceoperating a direction angle of the leveling base at the point P_(i+1)based on the encoder pattern read angle θ_(E) and an offset angle θ_(T)of the target unit around the vertical central axis with respect to theleveling base; (e) the scanner device operating coordinates of the pointP_(i+1) based on the direction angle of the leveling base at the P_(i+1)and the measured coordinates; (f) the scanner device moving the scannerdevice to the point P_(i+1) whose coordinates and direction angle becameknown through the steps (a) to (e), when there is a point to be observednext; and (g) the scanner device repeating the steps (a) to (e) bysetting i=i+1 after the step (f). The target unit includes thereflection target and the encoder pattern, the encoder pattern shows anangle in a circumferential direction of the central axis around thetarget unit, the leveling base is configured to selectively allow eitherof the target unit and the scanner device to be removably mounted so asto share a central axis in the vertical direction, and the offset angleof the target unit and the offset angle of the scanner device arerespectively known.

It is also preferable that the surveying method includes (h) a step,performed by the scanner device, of acquiring point cloud data of ameasurement range, at a point whose coordinates and direction anglebecame known by using the surveying method according to the aspectdescribed above.

In this description, the term “encoder pattern” is a pattern havingangle information in which a reference point is set to 0°. This patternmay include not only a pattern detectable by natural light but also apattern detectable by polarized light.

Benefit of Invention

According to the configuration described above, in a survey using aground-installed scanner, a new point can be determined less or withoutperforming observation of a known point or a backsight point.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a configuration schematic view of a surveying system accordingto an embodiment of the present invention.

FIG. 2 is a perspective view illustrating a state where a target unitaccording to the same embodiment is fitted to a leveling base.

FIG. 3A is an enlarged perspective view of an encoder pattern portion ofthe target unit in the same embodiment, and FIG. 3B is a view (partiallyomitted) of an encoder pattern of the encoder pattern portion, cut openat a reference point and planarly developed.

FIG. 4 is a configuration block diagram of a scanner device according tothe same embodiment.

FIG. 5 is a schematic view describing a mechanism for light transmissionand reception in a distance measuring unit and an encoder patternreading unit of the scanner device according to the same embodiment.

FIG. 6A is a perspective view of a leveling base according to the sameembodiment, and FIG. 6B is a plan view of the same leveling base.

FIG. 7 is a view describing a mounting structure of the target unit tothe leveling base of the same embodiment.

FIG. 8A, FIG. 8B and FIG. 8C are views illustrating the target unit, theleveling base, and the scanner device, respectively, and the manner inwhich they cooperate according to the same embodiment.

FIG. 9 is a flowchart of an example of point cloud data observationusing the surveying system according to the same embodiment.

FIG. 10A, FIG. 10B, FIG. 10C and FIG. 10D are views each describing adisposition of the scanner device and the target unit in the example ofpoint cloud data observation described above.

FIG. 11 is a flowchart of encoder pattern reading in the same pointcloud data observation.

FIG. 12A is a view describing a scanning position of the encoder patternby the scanner device of the same embodiment, and FIG. 12B is a graphillustrating results of output of reflected scanning light as a receivedlight amount distribution.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention are described withreference to the drawings. In the following description of theembodiments, the same components are provided with the same referencesigns, and overlapping description is omitted. In each drawing,components are enlarged and schematically illustrated as appropriate forconvenience of description, and which may not reflect actual ratios.

Embodiments 1. Overall Configuration of Surveying System

FIG. 1 is a view illustrating a schematic configuration of a surveyingsystem 100 to carry out a surveying method according to an embodiment ofthe present invention. The surveying system 100 includes a target unit10, a scanner device 30, and a leveling base 70.

2. Configuration of Target Unit

As illustrated in FIG. 2, the target unit 10 includes a reflectiontarget 11, a support member 12, an encoder pattern portion 13, and abase portion 14, and is removably mounted on the leveling base 70mounted on a tripod 2, and held vertically.

The reflection target 11 is a so-called 360-degree prism configured by,for example, radially combining a plurality of triangular pyramidprisms, and reflects light made incident from its entire circumference(360°) toward directions opposite to the incident directions. That is,the reflection target 11 reflects distance measuring light from thescanner device 30 toward the scanner device 30. The reflection target 11is not limited to the 360-degree prism, and a normal prism to be usedfor a survey may be used.

The support member 12 is, for example, a columnar member made of metalor resin, extending upward so as to have a fixed length from the baseportion 14. The support member 12 fixes and supports the encoder patternportion 13 and the reflection target 11 so that a central axis A of thesupport member passes through a center O_(E) (FIG. 3A) (of a base 13A)of the encoder pattern portion 13. A central axis of the base 13A andthe central axis A of the support member 12 that are common to eachother are configured to pass through the center O of the reflectiontarget 11. That is, the central axis A of the support member 12 is acentral axis of the target unit 10.

The encoder pattern portion 13 is configured by providing an encoderpattern 13B on a side circumferential surface of the base 13A that is ina short columnar shape. The base 13A is fixed between the support member12 and the reflection target 11 by a method such as, for example,screwing a threaded portion (not illustrated) formed on an outercircumference of the support member to a screw hole (not illustrated)formed at a center of the base 13A.

The encoder pattern 13B includes an angle information portion 131 and awidth information portion 132 above and adjacent to the angleinformation portion 131.

As illustrated in FIG. 3A and FIG. 3B, the angle information portion 131is a barcode-like pattern formed by disposing, for example, narrow-widthblack vertical lines 131 a with a width w₁ and wide-width black verticallines 131 b with a width w₂ at even pitches p on a white background bydefining the vertical lines 131 a as “0” and the vertical lines 131 b as“1” so as to generate an M-sequence recurring random number code. Theencoder pattern 13B is configured so that, by setting a direction RDfrom the center of the encoder pattern portion 13 to a reference pointRP (hereinafter, referred to as a “reference direction of the encoderpattern”) as 0°, an angle (hereinafter, referred to as an “encoderpattern read angle”) θ_(E) calculated from the pattern read by thescanner device corresponds to an absolute angle in a clockwisecircumferential direction around the central axis A of the supportmember 12, from the reference direction RD of the encoder pattern 13B.

The angle information portion 131 is configured so as to realize desiredresolution by changing a bit number.

The bit pattern is not limited to the M-sequence code, and bit patternssuch as a gray code and a pure binary code can be used, and these can begenerated by a publicly known method. However, use of the M-sequencecode is advantageous because it enables an increase in bit numberwithout increasing tracks in number, and realizes high resolution with asimple configuration.

The width information portion 132 includes a black zone 132 a with apredetermined height h₁ and a white zone 132 b with the same height. Theblack zone 132 a and the white zone 132 b respectively extend across theentire circumference of the encoder pattern portion 13 in thecircumferential direction.

The encoder pattern 13B can be provided in the encoder pattern portion13 by various publicly known methods that are used for forming patterns.The encoder pattern 13B may be provided by, for example, printing on awhite sheet by a method of general printing, such as inkjet printing,and sticking the sheet onto the side circumferential surface of the base13A. According to this method, the encoder pattern portion 13 can beformed by an extremely inexpensive and simple method. The encoderpattern 13B may be provided by being directly printed on a resin-madebase 13A. Alternatively, the encoder pattern 13B may be provided on ametal-made base 13A by a method such as painting or vapor deposition,etc.

In the illustrated example, the width information portion 132 isdisposed above and adjacent to the angle information portion 131.However, the positional relationship between the angle informationportion 131 and the width information portion 132 is not limited tothis, and the width information portion 132 may be disposed below theangle information portion 131.

The encoder pattern portion 13 is disposed below and adjacent to thereflection target 11. However, the positional relationship between theencoder pattern portion 13 and the reflection target 11 is not limitedto this, and other dispositions are possible as long as the encoderpattern portion 13 is disposed to be coaxial with the central axis A ofthe support member 12 passing through the center O of the reflectiontarget 11.

That is, the encoder pattern portion 13 may be disposed above thereflection target 11. The encoder pattern portion 13 and the reflectiontarget 11 may be disposed away from each other.

The base portion 14 is, for example, a columnar member made of metal orresin, which is larger in diameter than the support member 12, andprovided coaxially with the support member 12, and has dimensionsmatching a base mounting hole 74 of the leveling base 70. On a bottomsurface of the base portion 14, engagement projections 15 a, 15 b, and15 c (FIG. 7) that respectively engage with engagement holes 76 a, 76 b,and 76 c of the leveling base 70 as described later are provided atthree positions at even intervals in the circumferential direction withrespect to the central axis A of the support member 12.

On a side circumferential surface of the base portion 14, a positioningprojection 16 is provided so as to project in a radial direction.

3. Configuration of Scanner Device

FIG. 4 is a configuration block diagram of the scanner device 30. Thescanner device 30 is a so-called laser scanner, and includes a distancemeasuring unit 31, an encoder pattern reading unit 32, a rotating mirror33, a vertical rotation drive unit 34, a vertical angle detector 35, ahorizontal rotation drive unit 36, a horizontal angle detector 37, astorage unit 38, a display unit 39, an operation unit 41, an arithmeticcontrol unit 42, and an external storage device 43.

In appearance, as illustrated in FIG. 1, the scanner device 30 isinstalled via the leveling base 70 mounted on a tripod 2, in the samemanner as the target unit 10. The scanner device 30 includes a baseportion 6 a to be removably mounted on the leveling base 70, a bracketportion 6 b provided to be horizontally rotatable 360° around an axisH-H, and a telescope portion 6 c provided to be vertically rotatablearound an axis V-V in a concave portion 8 of the bracket portion 6 b.

In the base portion 6 a, the horizontal rotation drive unit 36 and thehorizontal angle detector 37 that detects a rotation angle around theaxis H-H of horizontal rotation are housed. The horizontal rotationdrive unit 36 is, for example, a motor, and the horizontal angledetector 37 is, for example, a rotary encoder. The horizontal rotationdrive unit 36 rotates the bracket portion 6 b around the axis H-H ofhorizontal rotation, and the horizontal angle detector 37 detects arotation angle of the bracket portion 6 b around the axis H-H ofhorizontal rotation with respect to the base portion 6 a, and outputs adetection signal to the arithmetic control unit 42.

A bottom portion of the base portion 6 a has the same configuration asthat of a bottom portion of the base portion 14 of the target unit 10.That is, the bottom portion is shaped in a columnar shape matching thebase mounting hole 74 of the leveling base 70, and the base portion 6 ais provided, on its bottom surface, with engagement projections 61 a, 61b, and 61 c (refer to FIG. 8C) having shapes matching engagement holes76 a, 77 b, and 76 c of the leveling base 70. On a side circumferentialsurface of the bottom portion of the base portion 6 a, a positioningprojection 62 is provided.

In the bracket portion 6 b, the vertical rotation drive unit 34, thevertical angle detector 35, the storage unit 38, and the arithmeticcontrol unit 42 are provided. The display unit 39 and the operation unit41 are provided outside the bracket portion 6 b.

The vertical rotation drive unit 34 is a motor, and is provided on anaxis V-V of vertical rotation. The telescope portion 6 c is configuredto rotate 360 degrees in the vertical direction in response to rotationof the vertical rotation drive unit 34. The vertical angle detector 35is, for example, a rotary encoder. The vertical angle detector 35 isprovided on an axis V-V of vertical rotation, and detects a rotationangle around the axis V-V and outputs a detection signal to thearithmetic control unit 42.

In the telescope portion 6 c, the distance measuring unit 31 and theencoder pattern reading unit 32 are housed. Inside the telescope portion6 c, a lens barrel (not illustrated) including the rotating mirror 33 isprovided, and an axis of horizontal rotation of the lens barrel iscoaxial with the axis H-H of horizontal rotation of the bracket portion6 b. The lens barrel is mounted in the telescope portion 6 c by a propermeans.

FIG. 5 is a view describing a mechanism for light transmission andreception of a distance measuring light 3 and a encoder pattern readinglight 4 in the distance measuring unit 31 and the encoder patternreading unit 32 of the present embodiment. The distance measuring unit31 includes a distance measuring light transmission and receivingoptical system 48 including a distance measuring light transmission unit44, a distance measuring light receiving unit 45, a beam splitter (notillustrated), a distance measuring light mirror 46, a distance measuringlight condenser lens 47, and the rotating mirror 33. The distancemeasuring light transmission unit 44 includes a light emitting element(not illustrated).

The light emitting element is, for example, a semiconductor laser or thelike, and emits a pulsed laser beam as distance measuring light 3. Theemitted distance measuring light 3 is reflected by the distancemeasuring light mirror 46, and further reflected by the rotating mirror33 and irradiated onto a measuring object. The rotating mirror 33 is adouble-sided mirror, and is driven by the vertical rotation drive unit34 to rotate around a vertical rotation axis V-V. Therefore, therotating mirror 33 and the vertical rotation drive unit 34 constitute ascanning unit 63 to scan the distance measuring light. The rotatingmirror 33 is, for example, a perforated double-sided mirror having arectangular or circular plate shape, but is not limited to this.

The distance measuring light 3 a retroreflected by the measuring objectenters the distance measuring light receiving unit 45 through therotating mirror 33, the distance measuring light mirror 46, and thedistance measuring light condenser lens 47. The distance measuring lightreceiving unit 45 is a light receiving element, for example, aphotodiode, etc. A portion of the distance measuring light split by theabove-described beam splitter enters the distance measuring lightreceiving unit 45 as internal reference light (not illustrated), andbased on the reflected distance measuring light 3 a and the internalreference light, a distance to an irradiation point is obtained by thearithmetic control unit 42.

By cooperation of a rotation of the rotating mirror 33 in the verticaldirection and a r rotation of the bracket portion 6 b in the horizontaldirection, two-dimensional scanning with the distance measuring light isperformed. Distance measurement data for each pulsed light is acquiredby the distance measuring unit 31, and angle measurement data for eachpulsed light is acquired by the vertical angle detector 35 and thehorizontal angle detector 37. Full-dome scanning is performed byrotating 270° including a vertex in the vertical direction and rotating360° in the horizontal direction, and thus, three-dimensional pointcloud data of the measurement range are acquired.

On the other hand, the encoder pattern reading unit 32 includes areading light transmission and receiving optical system 55 including areading light transmission unit 51, a reading light receiving unit 52, areading light mirror 53, and a reading light condenser lens 54. Thereading light transmission unit 51 includes a light emitting element(not illustrated), and emits a light beam with a wavelength differentfrom that of the distance measuring light 3, for example, a visiblelight, etc., as the encoder pattern reading light 4. The emitted encoderpattern reading light 4 is reflected by the reading light mirror 53. Theencoder pattern reading light is further reflected by the rotatingmirror 33 and irradiated onto the encoder pattern 13B. The reflection ofthe reading light 4 is performed by a surface of the rotating mirror 33on the reverse side of a surface that reflects the distance measuringlight 3.

Then, the reading light 4 a reflected by the encoder pattern 13B entersthe reading light receiving unit 52 through the rotating mirror 33, thereading light mirror 53, and the reading light condenser lens 54. Thereading light receiving unit 52 is a light receiving element, forexample, an avalanche photodiode, etc. A light receiving signal inputinto the reading light receiving unit 52 is output as a received lightamount distribution to the arithmetic control unit 42.

The storage unit 38 is, for example, a hard disk drive, and storesvarious programs for activating the scanner device 30. For example, thestorage unit stores 38 programs such as a sequence program to perform adistance measurement and an angle measurement, a point cloud datameasurement program for acquiring point cloud data by driving thescanning unit to rotationally irradiate distance measuring light andperforming operations of distance and angle measurements for each point,a target scanning program for scanning a periphery of the target andoperating coordinates of the reflection target 11, an encoder patternread angle operation program for reading the encoder pattern andoperating an encoder pattern read angle θ_(E), a direction angleoperation program for operating a direction angle based on the encoderpattern read angle θ_(E), and a coordinate operation program foroperating coordinates of the scanner device 30 on the basis of measuredcoordinates of the reflection target 11 and a direction angle of thescanner device, etc. In addition, the storage unit 38 storescorrelations between bit patterns represented by encoder patterns andangles, for example, in a table format.

The display unit 39 is, for example, a liquid crystal display or thelike, and displays operation status data and measurement results, etc.,obtained by the arithmetic control unit 42.

The operation unit 41 is a touch display, a keyboard, or the like, andinputs operation commands into the scanner device.

The arithmetic control unit 42 is, for example, a microcontrollerincluding a CPU, a ROM, and a RAM, etc., mounted on an integratedcircuit. The arithmetic control unit 42 is electrically connected to thedistance measuring unit 31, the encoder pattern reading unit 32, thevertical rotation drive unit 34, the vertical angle detector 35, thehorizontal rotation drive unit 36, the horizontal angle detector 37, thestorage unit 38, the display unit 39, and the operation unit 41.

Into the arithmetic control unit 42, angle detection signals from thevertical angle detector 35 and the horizontal angle detector 37 areinput, and light receiving signals from the distance measuring lightreceiving unit 45 and the reading light receiving unit 52 are input. Inaddition, a signal from the operation unit 41 in response to anoperator's operation is input.

The arithmetic control unit 42 drives the distance measuring lighttransmission unit 44, the reading light transmission unit 51, thevertical rotation drive unit 34, and the horizontal rotation drive unit36, and controls the display unit 39 that displays an operation statusand measurement results, etc.

The arithmetic control unit 42 includes, as functional units, a targetscanning performing unit 56 that performs target scanning to measure adistance and an angle by intensively irradiating distance measuringlight onto a peripheral range around the reflection target, andcalculates measured coordinates of the reflection target from thedistance measurement and angle measurement data, a point cloud dataacquisition unit 57 that acquires point cloud data of the measurementrange by operating results of the distance measurement and anglemeasurement performed for each point by rotationally irradiatingdistance measuring light onto the measuring object (range), an encoderpattern read angle operation unit 58 that operates an encoder patternread angle θ_(E) from a result of encoder pattern reading, a directionangle operation unit 59 that operates a direction angle based on anoffset angle θ_(T) of the target unit 10, an offset angle θ_(S) of thescanner device 30, and the encoder pattern read angle θ_(E), and acoordinate operation unit 60 that operates coordinates of a new point ina map coordinate system based on the measured coordinates of thereflection target 11 and the distance angle of the scanner device 30.

The external storage device 43 is, for example, a memory card, a harddisk drive, a USB memory, or the like, and may be fixed to or may beremovably provided in the arithmetic control unit 42. The externalstorage device 43 stores reflection target measurement data, point clouddata, angle measurement data, and encoder pattern read data, etc.

4. Configuration of Leveling Base

The leveling base 70 is a pedestal on which either the target unit 10 orthe scanner device 30 is selectively mounted, and has an automaticleveling function. The leveling base 70 is formed mainly of, asillustrated in FIG. 6A, a tripod mounting seat portion 71 to be mountedon a tripod, a leveler main body 72, and three leveling screws 73joining the tripod mounting seat portion 71 and the leveler main body72.

The leveler main body 72 includes a tilt sensor, a leveling screw drivemechanism, and a control unit, etc., which are not illustrated, and isconfigured to adjust the leveling screws 73 by automatically controllingthe drive mechanism based on tilt posture information of the tilt sensorso that the leveler main body 72 becomes horizontal. As an automaticcontrol mechanism of the leveler main body 72, a publicly knownconfiguration can be used as appropriate, so that detailed descriptionof the automatic control mechanism is omitted. In addition, the levelermain body 72 is provided with a level 77 to check a level state.

As illustrated in FIG. 6B, in an upper surface of the leveler main body72, a base mounting hole 74 for mounting the target unit 10 or thescanner device 30 is opened. In the base mounting hole 74, threeengagement holes 76 a, 76 b, and 76 c are provided at intervals of 120°in a circumferential direction around an installation position 75 of alaser centripetal device (not illustrated) provided at a central portionof the base mounting hole 74. At a portion of an outer rim portion ofthe leveler main body 72, a fitting groove 78 is formed.

As illustrated in FIG. 7, the target unit 10 is positioned in thecircumferential direction by the engagement holes 76 a, 76 b, and 76 cand the fitting groove 78, and mounted on the leveling base 70 so as toshare a central axis in the vertical direction. The target unit 10 isremovably locked to the leveling base 70 by pressing one engagementprojection 15 a by a plate spring locking mechanism not illustrated.

A mounting structure of the scanner device 30 onto the leveling base 70is also the same as the mounting structure of the target unit 10.

As a result, when the target unit 10 is mounted on the leveling base 70in the state illustrated in FIG. 8B, the reference direction RD of theencoder pattern portion 13 (that is, the target unit 10) deviates by anangle θ_(T) (hereinafter, referred to as an “offset angle θ_(T) of thetarget unit 10”) counterclockwise in the circumferential direction froma reference direction D_(L) of the leveling base 70 (hereinafter,referred to as a “direction D_(L) of the leveling base 70”) (FIG. 8A).In FIG. 8A to FIG. 8C, the reference signs O_(T), O_(L), and O_(S)respectively denote the centers of the target unit 10, the leveling base70, and the scanner device 30.

Similarly, when the scanner device 30 is mounted on the leveling base 70in the state illustrated in FIG. 8B, a reference direction D_(S) of thescanner device 30 (hereinafter, referred to as a “direction D_(S) of thescanner device 30”) deviates by a predetermined angle θ_(S)(hereinafter, referred to as a “offset angle θ_(S) of the scanner device30”) counterclockwise in the circumferential direction from thedirection D_(L) of the leveling base 70 (FIG. 8C).

Here, clockwise angles relative to the north of the reference directionRD of the target unit 10, the direction D_(S) of the scanner device 30,and the direction D_(L) of the leveling base 70 are respectively adirection angle of the target unit 10, a direction angle of the scannerdevice 30, and a direction angle of the leveling base 70.

The offset angle θ_(T) of the target unit 10 and the offset angle θ_(S)of the scanner device 30 are known in advance through measurement ordesign, and stored in the storage unit 38. When the scanner device 30 isinstalled at a known point and reads an encoder pattern read angle θ_(E)in a state where the direction angle is set to a known value α, theencoder pattern read angle θ_(E) can be expressed by a function of α.Therefore, a direction angle of the leveling base 70 can be obtainedbased on the encoder pattern read angle θ_(E) and the offset angle θ_(T)of the target unit 10. Further, when the direction angle of the levelingbase 70 is obtained, based on the offset angle θ_(S) of the scannerdevice 30, a direction angle of the scanner device 30 mounted on theleveling base 70 can be obtained.

The above-described settings of the direction D_(L) of the leveling base70 and the direction D_(S) of the scanner device 30 are examples in thepresent embodiment, and as described above, by performing positioning inthe circumferential direction by using the fitting groove 78 and theengagement holes 76 a, 76 b, and 76 c of the leveling base 70 andsetting a horizontal angle around the central axis A to a predeterminedangle, the reference direction RD of the encoder pattern portion 13, thedirection D_(L) of the leveling base 70, and the direction D_(S) of thescanner device 30 can be set to have a definite relationship.

The relationships in the vertical direction between the reflectiontarget 11 of the target unit 10 and the scanner device 30; and theleveling base 70 are respectively fixed. And the positionalrelationships in the vertical direction are known. Thus, by obtainingcentral coordinates of the reflection target 11 mounted on the levelingbase 70, so that coordinates of the leveling base 70 are obtained. Basedon the coordinates of the leveling base 70, coordinates of the scannerdevice 30 mounted on the leveling base 70 are also obtained.

5. Survey of Observation Point and Observation of Point Cloud Data 5-1.Entire Operation

FIG. 9 is a flowchart of a survey of an observation point andobservation of point cloud data performed by using the surveying system100 according to the present embodiment.

A case of observation of point cloud data in each of the spacesillustrated in FIG. 10A to FIG. 10D is described by way of example. Inthe figures, a black triangle denotes a known point, a white circledenotes an observation point being a new point, a black circle denotesan observation point whose coordinates were obtained throughmeasurement, and a black star denotes a point at which point cloud datahave been completely acquired (full-dome scanned). At each point, theleveling base 70 mounted on a tripod is installed in advance. Englishletters T and S attached to each point respectively show which of thetarget unit 10 or the scanner device 30 is mounted on the leveling base70 at each point. An arrow means that the reflection target 11 installedat an end point of the arrow was target-scanned by the scanner device 30installed at a start point.

Values of the offset angle θ_(T) of the target unit 10 and the offsetangle θ_(S) of the scanner device 30 are known in advance throughmeasurement or design and stored in the storage unit 38. Coordinates anda direction angle of the leveling base installed at a first observationpoint P₀ are to be obtained by a backsight-point-and-instrument-pointmethod.

When starting observation, first, in Step S101, the scanner device 30 ismounted on the leveling base 70 installed at the first observation pointP₀ (x₀, y₀, z₀) being a known point. At this time, the target unit 10 isinstalled at a backsight point A (FIG. 10A).

Next, in Step S102, the reflection target 11 at the backsight point A istarget-scanned with the scanner device 30, and measured coordinates ofthe reflection target 11 are acquired.

Next, in Step S103, the arithmetic control unit 42 operates a directionangle of the scanner device at the point P₀ and coordinates P₀ (x₀, y₀,z₀) in a map coordinate system.

Steps S101 to S103 are the same as in a conventional method, and thesesteps may be performed by a backward intersection method, that is bypreparing two or more known points and setting a point whose coordinatesare unknown as a first observation point, without limiting to abacksight-point-and-instrument-point method. In this case, in Step S102,the known points are target-scanned, and in Step S103, based on a resultof the target scanning, a direction angle of (the scanner device 30installed at) the first observation point P₀ is operated, andcoordinates in a map coordinate system are operated.

Next, in Step S104, an operator mounts the target unit 10 (reflectiontarget 11) on the leveling base 70 installed at a new point P₁ to be anext observation point, and inputs that fact from the operation unit.

Next, in Step S105, the reflection target 11 installed at the point P₁is target-scanned with the scanner device 30, and measured coordinatesof a center of the reflection target 11 are acquired.

Next, in Step S106, the coordinate operation unit 60 operatescoordinates (x₁, y₁, z₁) in the map coordinate system of (the scannerdevice 30 at) the point P₁ based on a result of the target scanning ofthe point P₁ and the direction angle of the point P₀.

Next, in Step S107, the scanner device 30 reads the encoder pattern 13B,and operates an encoder pattern read angle θ_(E). Details of the readingof the encoder pattern 13B are described later.

Next, in Step S108, the direction angle operation unit 59 operates adirection angle of the leveling base 70 at the point P₁ based on theencoder pattern read angle θ_(E) and the offset angle θ_(T) of thetarget unit 10.

Next, in Step S109, the scanner device 30 performs a point cloud dataacquisition mode, and performs full-dome scanning.

Next, in Step S110, the scanner 30 determines whether or not there is apoint to be measured next.

When there is a point to be measured next (Yes), in Step S111, theoperator removes the target unit 10 from the leveling base 70 at thepoint P₁, and mounts the target unit 10 on the leveling base 70 at thenext observation point P₂. The target unit 10 at the point P₂ may be anew target unit. At this time, the scanner device 30 may display amessage, etc., prompting the operator to move the scanner device on thedisplay unit 39.

In Step S111, when the operator inputs completion of the movement withthe operation unit, the scanner device 30 sets i=2 as instrument pointinformation and shifts the processing to Step S112, and operates adirection angle of the scanner device 30 based on the direction angle ofthe leveling base 70 acquired in Step S108 and the offset angle θ_(S) ofthe scanner device 30. At this time, it is also possible that operationof the direction angle of the leveling base 70 in Step S108 is omitted,and a direction angle of the scanner device 30 is directly operated fromthe encoder pattern read angle θ_(E), the offset angle θ_(T) of thetarget unit 10, and the offset angle θ_(S) of the scanner device 30.

Next, the processing returns to Step S104 (FIG. 10B). Here, the operatormounts the target unit 10 on the leveling base 70 at the point P₂, andinputs that fact into the scanner.

Thus, until it is determined that there is no longer a next observationpoint in Step S110, Steps S111, S112, and S104 to S110 are repeated, andthe measurement is advanced for points P₂ and P₃ as illustrated in FIG.10C and FIG. 10D.

Then, when there is no next observation point in Step S110 (No), theobservation is ended.

The direction angles and coordinate data, etc., obtained through targetscanning, full-dome scanning, encoder pattern reading, and variousarithmetic operations, are stored in the storage unit 38 in associationwith information on observation points, or output to the externalstorage device 43. Alternatively, a configuration is also possible inwhich the scanner device 30 is provided with a communication unit, andthese data are transmitted to an external data processing device such asa personal computer.

After the point cloud data at each observation point, the coordinatedata at each observation point, and the direction angle data of thescanner device 30 are transferred into the external data processingdevice, the point cloud data are converted into an absolute coordinatesystem, and through registration processing, three-dimensional shapedata are obtained.

As illustrated in FIG. 10C, it is also possible that, at the point P₂, aplurality of target units 10 are used and respectively installed at thepoint P₃ and point P₅, and after coordinates and a direction angle ofthe point P₃ are acquired, subsequently, coordinates and a directionangle of the point P₅ are acquired as illustrated by the dashed line.

According to the surveying system of the present embodiment, in a statewhere coordinates and a direction angle become known, by acquiringcoordinates of a new point by target scanning, and acquiring an encoderpattern read angle, a direction angle of the leveling base at the newpoint can be acquired and a direction angle of the scanner devicemounted on the leveling base can be acquired without target scanning ofa backsight point or a known point. Therefore, except for the firstobservation point, there is no need to target-scan a backsight point orknown point to obtain coordinates and a direction angle of a new point,so that the time required for the survey can be shortened.

For example, when a survey in each space illustrated in FIG. 10A to FIG.10D is assumed, according to the conventionalbacksight-point-and-instrument-point method, observation of a backsightpoint at each point is necessary, so that target scanning needs to beperformed 11 times (twice for each of the points P₀, P₁, and P₃, threetimes for the point P₂, and once for each of the point P₄ and P₅).However, according to the present embodiment, target scanning isperformed only 6 times. Therefore, the time required for target scanningcan be shortened, and as a result, the time required for the entireobservation can be shortened.

To obtain coordinates and a direction angle of a new point, there is noneed to target-scan a backsight point or known point, and this isadvantageous in an indoor space that has poor visibility such as in FIG.10A to FIG. 10D.

This is because, for example, when a survey in a space as illustrated inFIG. 10A to FIG. 10D by a conventional backward intersection method isassumed, it is difficult to prepare two or more known points for eachnew point. To prepare two or more known points, observation points needto be increased, and observation point setting becomes troublesome, andthe time required for the entire observation increases. On the otherhand, according to the present embodiment, only visibility between a newpoint and a next new point is required, and there are fewer restrictionsin preparation of new points. Therefore, there is no need to perform aknown point setting operation and an observation operation more thannecessary.

Moreover, as described above, according to the surveying system of thepresent embodiment, acquisition of point cloud data by the scannerdevice installed at an observation point whose coordinates and adirection angle are known is particularly advantageous because thisenables efficiently performing the entire observation of point clouddata.

5-2. Encoder Pattern Reading

Here, the reading of the encoder pattern 13B in Step S107 is describedwith reference to FIG. 11, FIG. 12A and FIG. 12B.

When starting encoder pattern reading, in Step S201, under control ofthe arithmetic control unit 42, the reading light transmission unit 51transmits a reading light 4 to scan a periphery of the encoder patternportion 13 at intervals of, for example, a height h₃ as illustrated inFIG. 12A.

The arithmetic control unit 42 sets scanning conditions based ondistance measurement data of the reflection target 11 acquired in StepS105 and known dimensions of the encoder pattern portion 13.

For example, a height h₃ set to be, for example, shorter than the heighth₁ of the black zone 132 a and the white zone 132 b of the widthinformation portion 132 (FIG. 3B) and shorter than a half h₂/2 of theheight h₂ of the vertical lines 131 a and 131 b (FIG. 3B) is preferablebecause this height h₃ enables reliable scanning of both of the widthinformation portion 132 and the angle information portion 131.

Next, in Step S202, the reading light reflected by the encoder pattern13B is received by the reading light receiving unit 52, and a lightreceiving signal is output as a received light amount distribution tothe arithmetic control unit 42. Light reflected by a black portion ofthe encoder pattern is received as weak light and light reflected by awhite portion is received as intense light, so that in the receivedlight amount distribution, the value becomes small at a black portion,and becomes large at a white portion. Therefore, the received lightamount distributions at respective positions I to V in FIG. 12A are, forexample, as illustrated in FIG. 12B.

Next, in Step S203, from the received light amount distributionsacquired in Step S202, results of reading of the width informationportion 132 are extracted. In detail, a region corresponding to areceived light amount smaller than a predetermined threshold isdetermined as a black portion, a region corresponding to a receivedlight amount larger than the predetermined threshold is determined as awhite portion, and a region in which at least one of the black portionand the white portion continues for a length corresponding to a diameterL of the encoder pattern portion calculated from the result of targetscanning acquired in Step S105 and known dimensions of the encoderpattern portion, is determined as the width information portion 132.

As a result, in FIG. 12B, it is found that pixel rows I and IIcorrespond to the width information portion 132. Then, from the width Lof the encoder pattern 13B detected (diameter of the encoder patternportion 13), a center position A of the encoder pattern 13B isidentified.

Next, in Step S204, the encoder pattern read angle operation unit 58calculates correlations of received light amount distributions at therespective positions from the received light amount distributionsacquired in Step S202, and ones having correlations higher than apredetermined value are extracted as the results of reading of the angleinformation portion 131.

In the example illustrated in FIG. 12B, at the scanning positions III toV, patterns of the received light amount distributions have highcorrelations with each other. Therefore, the light received amountdistributions at the scanning positions III to V are found to be resultsof reading of the angle information portion 131.

Then, the extracted received light amount distributions at the scanningpositions III to V are added up in the vertical direction, and meanvalues are calculated. A portion with a calculated mean value smallerthan a predetermined threshold is determined as a black portion, and awidth of the black portion is obtained. Next, whether the obtained widthvalue corresponds to a narrow width or a wide width of the encoderpattern 13B is determined, and a region with the width determined as anarrow width is read as a bit “0,” that is, a vertical line 131 a, and aregion with the width determined as a wide width is read as a bit “1,”that is, a vertical line 131 b.

By calculating received light amount distributions as mean values of theplurality of positions in this way, for example, as in the case of thescanning position IV, even when noise such as misalignment in thehorizontal position of a received light amount distribution occurs, theinfluence of this misalignment can be reduced, and reading accuracy canbe improved.

The encoder pattern portion 13 is columnar, so that the vertical linewidths w₁ and w₂ and the pitch p are observed to be narrower than actualwidths with increasing distance from the center. For example, in FIG.3A, the width w_(2a) of the wide-width vertical line 131 b ₁ near thecenter is observed to be equal to the width (actual width) w₂ of thewide-width vertical line 131 b illustrated in the developed view of FIG.3B. On the other hand, the width web w_(2b) of the wide-width verticalline 131 b ₂ farthest from a central portion is observed to be narrowerthan the actual width w₂. The same applies to the width w₁ and the pitchp. Therefore, it is preferable that the widths w₁ and w₂ are set so thatranges of changes in widths w₁ and w₂ do not overlap each other inconsideration of the influence in which an observed width changesaccording to disposition.

Next, in Step S205, the encoder pattern read angle operation unit 58calculates an encoder pattern read angle θ_(E) by comparing a bitpattern included in a predetermined width R extending to the left andthe right from a center set at the center position A of the encoderpattern 13B obtained in Step S203, that is, a bit pattern represented bya predetermined bit number of vertical lines (for example, 10 lines.Representing a bit pattern “11010010100” in the illustrated example)included in the region of the predetermined width R, with thecorrelations between bit patterns and angles stored in the storage unit38. Next, the processing shifts to Step S107.

6. Modification

The above-described embodiment can be modified as follows.

For example, the encoder pattern 13B is not limited to a black and whitepattern, and may be formed of a combination of colors with clearcontrast. In addition, it is also possible that the encoder pattern isconfigured as an encoder pattern identifiable not just by visible lightbut by polarized light and a polarizing filter is provided on an opticalpath of the encoder pattern reading light receiving unit so as to enablerecognition of the pattern.

It is also possible that, in place of the encoder pattern reading unit,a camera is provided, and a peripheral image of the encoder pattern 13Bis imaged, and from a pattern of pixel values of the image, the encoderpattern is read.

Embodiments of the present invention are described above, and theabove-described embodiments are just examples, and can be combined basedon knowledge of a person skilled in the art. The above-describedembodiments can be variously changed without departing from the spiritof the invention. As a matter of course, the scope of rights of thepresent invention is not limited to the above-described embodiments.

REFERENCE SIGNS LIST

-   10 Target unit-   11 Reflection target-   13B Encoder pattern-   30 Scanner device-   31 Distance measuring unit-   32 Encoder pattern reading unit-   35 Vertical angle detector (angle detector)-   37 Horizontal angle detector (angle detector)-   42 Arithmetic control unit-   63 Scanning unit-   70 Leveling base-   100 Surveying system

What is claimed is:
 1. A surveying system comprising: a target unitincluding a reflection target and an encoder pattern showing an angle ina circumferential direction around a central axis of the target unit; ascanner device including a distance measuring unit configured to performa distance measurement by transmitting distance measuring light andreceiving reflected light, a scanning unit configured to rotationallyirradiate the distance measuring light onto a measurement range, and anangle detector configured to detect an irradiation direction of thedistance measuring light, so as to acquire point cloud data and acquiremeasured coordinates of the reflection target by performing targetscanning, the scanner device including an encoder pattern reading unitconfigured to optically read the encoder pattern, and an arithmeticcontrol unit configured to operate an encoder pattern read angle basedon a result of encoder pattern reading; and a leveling base configuredto selectively allow either of the target unit and the scanner device tobe removably mounted so as to share a central axis in a verticaldirection, and having offset angles, being known, around the centralaxis with respect to each of the target unit and the scanner device whenthe target unit or the scanner device is mounted, wherein the arithmeticcontrol unit is configured to calculate a direction angle of theleveling base based on the encoder pattern read angle of the target unitinstalled by mounting on the leveling base and the offset angle of thetarget unit, and calculate coordinates of an installation point of thetarget unit based on the measured coordinates of the reflection targetof the target unit installed by mounting on the leveling base and thedirection angle, and the arithmetic control unit is configured tocalculate a direction angle of the scanner device based on the offsetangle of the scanner device and the direction angle of the leveling baseon which the scanner device is mounted.
 2. A scanner device comprising:a distance measuring unit configured to perform a distance measurementby transmitting distance measuring light and receiving reflected light;a scanning unit configured to rotationally irradiate the distancemeasuring light onto a measurement range; an angle detector configuredto detect an irradiation direction of the distance measuring light; anencoder pattern reading unit configured to optically read an encoderpattern provided in a target unit, the target unit including areflection target and removably mounted on a leveling base so as toshare a central axis in the vertical direction, and the encoder patternshowing an angle in a circumferential direction around the central axisof the target unit; and an arithmetic control unit, and the scannerdevice removably mounted on the leveling base so as to share the centralaxis in the vertical direction, wherein the leveling base is configuredto have offset angles around the central axis when the scanner device orthe target unit is mounted, and the offset angles being known, thearithmetic control unit is configured to acquire point cloud data andoperate measured coordinates of the reflection target by target-scanningthe reflection target, operate the encoder pattern read angle from aresult of reading of the encoder pattern of the target unit mounted onthe leveling base, and based on the encoder pattern read angle and theoffset angle of the target unit, operate a direction angle of theleveling base, calculate coordinates of an installation point of thetarget unit based on measured coordinates of the target unit mounted onthe leveling base and installed and the direction angle, and calculate adirection angle of the scanner device based on the offset angle of thescanner device and the direction angle of the leveling base on which thescanner device is mounted.
 3. A target unit comprising: a reflectiontarget; and an encoder pattern showing an angle in a circumferentialdirection around a central axis of the target unit, configured to beremovably mounted on a leveling base so as to share a central axis inthe vertical direction, and configured to be, in a mounted state on theleveling base, positioned in the circumferential direction around thecentral axis and have an offset angle, being known, around the centralaxis.
 4. A surveying method comprising the steps of: (a) a scannerdevice calculating a direction angle of the scanner device based on anoffset angle θ_(S) of the scanner device around a vertical central axiswith respect to a leveling base, the scanner device mounted on theleveling base installed at a position P_(i) whose coordinates anddirection angle are known; (b) the scanner device scanning, at the pointP_(i), a reflection target of a target unit mounted on the leveling baseinstalled at a point P_(i+1) to be observed next, and operating measuredcoordinates of the reflection target; (c) the scanner device reading anencoder pattern of the target unit installed at the point P_(i+1), andoperating an encoder pattern read angle θ_(E) based on a result ofreading; (d) the scanner device operating a direction angle of theleveling base at the point P_(i+1) based on the encoder pattern readangle θ_(E) and an offset angle θ_(T) of the target unit around thevertical central axis with respect to the leveling base; (e) the scannerdevice operating coordinates of the point P_(i+1) based on the directionangle of the leveling base at the P_(i+1) and the measured coordinates;(f) the scanner device moving the scanner device to the point P_(i+1)whose coordinates and direction angle became known through the steps (a)to (e), when there is a point to be observed next; and (g) the scannerdevice repeating the steps (a) to (e) by setting i=i+1 after the step(f), wherein the target unit is configured to include the reflectiontarget and the encoder pattern, the encoder pattern shows an angle in acircumferential direction around the central axis of the target unit,the leveling base is configured to selectively allow either of thetarget unit and the scanner device to be removably mounted so as toshare a central axis in the vertical direction, and the offset angle ofthe target unit and the offset angle of the scanner device arerespectively known.
 5. A surveying method comprising: (h) a step, of thescanner device acquiring point cloud data of a measurement range, at apoint whose coordinates and direction angle became known by using thesurveying method according to claim 4.